The present invention is directed generally to apparatus and methods for uniquely assigning and utilizing conventionally locally-significant identifiers in a multi-protocol interworked network as global identifiers.
A large portion of networking traffic in the world is handled by interworked networks, which involves the transfer of data across networks that follow different network protocols. An important example of interworking is the interconnection of Frame Relay (FR) networks and Asyncrhononous Transfer Mode (ATM) networks.
A typical configuration of an FR-ATM service interworked network is a hub-and-spoke configuration such as is shown in FIG. 1. FR-ATM service interworked hub-and-spoke networks are often used by customers that require communication between a relatively large number of remote sites and a small set of data center hub sites. FR-ATM service interworking provides a means of bundling low-speed Permanent Virtual Circuits (PVCs) from remote sites into high-speed (e.g., DS3) data center access links.
In a hub-and-spoke network such as network 100, FR remote sites 101a-b are connected to ATM edge nodes 103a-b via FR PVCs, and ATM remote site 101c is connected directly to an ATM edge node 103c. These FR PVCs are established by FR network access shelves (NASs) 102a-b. Each FR NAS 102a-b has a plurality of network access ports for connecting to FR remote sites. The FR NAS bundles FR data together from the various network access ports, performs protocol conversion, and forwards the bundled and converted data to an ATM edge node via a feeder trunk (e.g., a single DS-3). The ATM edge nodes 103a-c provide access to the network cloud of switches and trunks that transport PVCs to an FR-ATM service gateway user-to-network/network-to-network (UNI/NNI) interface. The PVCs pass through the service gateway and enter the ATM network cloud. The ATM network cloud delivers the PVCs to the destination ATM edge nodes.
Each remote site and each ATM edge node is identified by one or more identifiers. In portions of the network using the FR protocol, the identifier is called a Data Link Connection Identifier (DLCI). In portions of the network using the ATM protocol, two identifiers, a Virtual Path Identifier (VPI) and a Virtual Channel Identifier (VCI), are used in conjunction. Each of these DLCI, VPI, and VCI identifiers is selected from a limited range of possible values and is either located in the header of, or encapsulated within, a message sent through the network.
Each PVC is terminated at one end by a remote site having an assigned DLCI and at the is other end by an ATM edge node having an assigned VPI/VCI. However, each of these identifiers typically only has local significance. In other words, one particular network element may interpret a particular DLCI (or VPI/VCI) to identify one particular PVC associated with one network access port, while another different network element may interpret the same DLCI (or VPI/VCI) to identify another different PVC associated with a different network access port. Network protocols conventionally using locally-significant identifiers are referred to herein as local network protocols.
FIG. 2 illustrates an example of conventional local addressing (i.e., using a local network protocol) in an FR-ATM service interworked network 200. The interworked network 200 includes an FR network 201 interconnected with an ATM network 202. The FR network 201 includes FR sites A and B, and the ATM network 202 includes ATM sites X and Y. In order transmit data to ATM site X FR site A would use the local outgoing path defined by, e.g., DLCI=100, and FR site B would use the local outgoing path defined by, e.g., DLCI=101. In the other direction, ATM site X would use the local outgoing path defined by, e.g., VPI/VCI 2/1035 to transmit data to FR site A, and ATM site X would use the local outgoing path defined by, e.g., VPI/VCI 3/1060 to transmit data to FR site A. The DLCIs and VPI/VCIs are different for different sites because the DLCIs and VPI/VCIs are interpreted locally. Thus, the use of such local identifiers provides a scheme for selecting a local outgoing path.
The use of FR-ATM service interworking conventionally requires the assignment and use of both FR DLCI values and ATM VPI/VCI values, each of which has significance only at the local FR or ATM site. A problem with this local addressing scheme is that customers who utilize interworked networks must often handle multiple different sets of identifiers. Customers often find the non-unique assignment of multiple different sets of identifiers to be troublesome and difficult to manage.
There is therefore a need for a satisfactory method for globally assigning network-wide global identifiers for sites in heterogeneous networks (e.g., networks having FR and ATM sites). It would be a further benefit to be able to assign and utilize such global identifiers in a way that is compatible with existing network equipment and protocols.
The present invention solves at least the above-identified problems of the prior art. A global addressing and identifier assignment scheme is presented herein. The scheme introduces a global (e.g., throughout the entire interworked network) interpretation for multiple identifiers within an interworked network. The term xe2x80x9cglobal identifierxe2x80x9d or xe2x80x9cglobal addressxe2x80x9d is used herein to describe an assignment by a service provider and/or customer of conventionally local identifiers in a manner that permits meaningful reference to the assigned values from remote locations.
Thus, according to one aspect of the present invention, instead of serving as locally significant identifiers for routing traffic to remote sites, the conventionally local identifiers may be interpreted as global identifiers (a.k.a. global addresses) for remote destination sites. For example, regardless of whether a destination site is a frame relay (FR) or asynchronous transfer mode (ATM) site, source FR sites may use the destination site""s global Data Link Connection Identifier (G-DLCI), and source ATM sites may use the destination site""s global Virtual Path Identifier/Virtual Channel Identifier (G-VPI/VCI), for routing traffic to the destination site. These global identifiers may be used in FR-to-FR transmissions as well as ATM-to-ATM transmissions. Further, ATM network nodes may continue to use the VCI/VPI to identify a destination site, and FR nodes may continue to use the DLCI to identify a destination site, just as in conventional networks, except that the identifiers are globally, instead of locally, assigned.
According to another aspect of the invention, a network-wide global addressing and identifier assignment method for interworked networks is provided, along with various exemplary embodiments of such a method. For example, in an FR-ATM service interworked network, a unique global DLCI and a unique global VPI and/or VCI may be assigned for each customer site in the interworked network, regardless of whether the site is an FR site or an ATM site.
Global identifiers may be preferably defined and assigned to each site in order to maximize the number of unique global identifiers available, since re-use of DLCIs and/or VPI/VCIs introduces the potential for confusion. Global identifier assignment schemes preferably should also effectively handle cases where the number of customer locations exceeds the number of distinct values available within an identifier (e.g., DLCI) usable range. In some assignment schemes, overlapping ranges of values for each protocol may be identified and taken into consideration in assigning the addresses such that each node has an identifier of a first protocol and an identifier of a second protocol having identical values and/or values that are otherwise related to each other in some way. In further assignment schemes, assignments may be made sequentially so that assignments can easily be performed automatically by a computer.
Assignments may be made such that there is no overlap between assigned global identifiers (i.e., each site has unique global identifiers). For example, each FR site may be assigned a global VPI/VCI identifier from a first range of available VCI/VPI values, and each ATM site may be assigned a global VCI/VPI identifier from a second range of available VPI/VCI values, the first range of VCI/VPI values and the second range of VCI/VPI identifiers being mutually exclusive ranges. Similarly, each FR site may also be assigned a global DLCI identifier from a first range of DLCI values, and each ATM site may be assigned a global DLCI identifier from a second range of DLCI values, the first range of DLCI values and the second range of DLCI values being mutually exclusive ranges. However, the various ranges of identifiers do not necessarily need to be mutually exclusive for a global assignment, so long as the assignments are globally unique for each site in the network. Any collisions that may occur between assigned identifiers during the assignment process may be removed and/or resolved manually and/or automatically by identifying the collisions and reassigning one or more identifiers in such a way that avoids the collision.
Thus, aspects of the present invention define a method comprising the steps of assigning a first address of a first network protocol to each of a first plurality of sites of a first network and to each of a second plurality of sites of a second network interworked with the first network, the first network conforming to the first network protocol and the second network conforming to a second network protocol different from the first network protocol; and assigning a second address of the second network protocol to each of the first plurality of sites and to each of the second plurality of sites, wherein a combination of the first and second addresses assigned to each of the first and second plurality of sites is globally unique to each of the first and second plurality of sites.
Further aspects of the present invention define, in an interworked network comprising a first network conforming to a first local network protocol interworked with a second network conforming to a second local network protocol different from the first local network protocol, a method comprising the steps of setting an identifier in a message of the first local network protocol destined for a destination site of the interworked network to be equal to a unique value associated with the destination site, regardless of whether the destination site is a site of the first network or of the second network; interpreting the identifier of the first local network protocol to be a global address of the destination site, the global address being unique within the interworked network; and forwarding the message to the destination site according to the global address.
Still further aspects of the present invention define an interworked network comprising a first network conforming to a first local network protocol interworked with a second network conforming to a second local network protocol different from the first local network protocol, the interworked network comprising a destination site; a first site of the first network configured to set an identifier in a message of the first local network protocol destined for the destination site to be equal to a unique value associated with the destination site, regardless of whether the destination site is a site of the first network or of the second network, and further configured to interpret the identifier of the first local network protocol to be a global address of the destination site, the global address being unique within the interworked network; and a plurality of sites including the first site configured to forward the message to the destination site according to the global address.
The above aspects of the present invention may be implemented to provide a customer with a set of maximally unique network-wide global identifier assignments for an interworked network. The global identifier assignment method of the present invention may be manually implemented and/or supported by automated provisioning tools. Such global identifier assignments are useful for both homogeneous (e.g., FR-FR or ATM-ATM and heterogeneous (e.g., interworked) configurations. In the example of an FR-ATM service interworked network, the present invention allows for the evolution from lower speed FR site interfaces to higher speed ATM site interfaces with minimal modifications to existing site FR and/or ATM identifier assignments.
It will become obvious to one of ordinary skill in the art reading this specification that the above-described aspects of the present invention can be readily expanded with very little experimentation to be utilized in heterogeneous networks that use more than two different protocols and that use any number of identifiers. Further, although this specification specifically addresses FR-ATM service interworked networks, the present invention is applicable to any homogeneous or heterogeneous network using any one or more network protocols, including, but not limited to, FR and/or ATM.